Growing season length as an indicator of climatic variations?
The growing season is considered by some to be a simple and yet significant indicator of the impact of hemispheric temperature variations at the local level. Yet, the effect of the use of different definitions of the growing season has never been determined.
In the present paper, time series of the length of differently defined growing seasons at four Wisconsin stations are compared. The results show that their lengths have fluctuated in a variety of patterns over the past 80 years. Two growing seasons which showed a significant trend did not agree on its direction. The reason for this disparity is that trends in maximum and minimum temperatures are not necessarily of the same sign at different times of the year. These findings suggest that the length of the growing season is not the simple climatic indicator it has been assumed to be.